Research has shown that approximately 10% of captive, individually housed monkeys have had some veterinary record of self-injurious behavior (SIB) within their lifetime. Given the idiosyncratic and heterogeneous nature of SIB, its seems unlikely that a single cause will be discovered. The purpose of this investigation was to identify possible risk factors for SIB by examining the demographic, environmental, developmental, and behavioral correlates of SIB. Examination of the colony records and behavioral assessments of 188 male individually housed rhesus monkeys at the NERPRC (14% assessed as showing self-biting behavior) yielded 3 potential risk factors. First, SIB monkeys spent more time in individual cages than controls (6.4 years versus 4.2 years). Second, SIB monkeys were individually-housed at a younger age than controls (16.2 months versus 28.5 months); suggesting an increased vulnerability to individual housing for younger animals. And third, SIB monkeys were moved into different cages within the same room more often than controls (3.5 moves versus 1.7 moves). Whereas individual housing may be causally linked to the development of SIB, it is unclear whether movement of animals to different cages was a cause or a consequence of SIB. Nevertheless, these results support the ideas that certain rearing and housing conditions as well as excessive disruption of daily routines may either cause or exacerbate self-injurious behavior in macaques.